I have the same problem. I've contacted the support today and I'm waiting for a solutions indeed response.
I have a lot of synthesizers, including the new Novation Ultranova, and the only synth that give me noises is the Virus Snow. So I think it is not a ground problem in fact, maybe the Virus synths are more susceptible to absorve noises... Not problem if Access assume that. What we want? Well, I need to keep trying in collaboration of Access Music and find the best solution or workaround that will get me rid of these annoying noises. ie.: A X-Hum adapter to the computer is a good solution?
Cristiano Keller